1. Field of the Invention
The present invention relates to methods useful for securing intersections formed by crossed strands of medical devices, such as woven stents. More particularly, the present invention relates to methods that include the use of securing materials to secure intersections formed by crossed strands of medical devices, and the devices formed thereby.
2. Description of Related Art
Medical devices serve a variety of uses in the treatment of various vascular and non-vascular disorders. Stents are one example of such medical devices. A stent is a device that may be placed within an internal body structure, such as a blood vessel, to maintain the patency of the internal body structure. For example, when a blood vessel becomes weak and contracted due, for example, to disease and begins to collapse, a stent may be inserted into the blood vessel, placed at the weak or diseased location, and will serve to prop open the weak or diseased portion of the blood vessel in order to allow blood to continue flowing. Various graft materials may also be coupled to stents to form what some term stent grafts. These stents grafts may be thought of as woven frames that have biocompatible jackets coupled to the frames. When an internal body structure such as a blood vessel becomes weak and expands, thereby creating a conduit with a weak, ballooned-out segment, a stent graft may be placed across the ballooned-out segment in order to restore the proper flow of fluid through the body structure.
The types of medical devices just described are often woven out of strands of biocompatible material of some kind, as are certain metals. One such woven medical device, in particular a woven stent, is the subject of U.S. Pat. No. 4,655,771 to Wallsten (hereinafter “the Wallsten patent”), which is hereby expressly incorporated herein by reference. A version of the subject of this patent is marketed as the WALLSTENT, which is manufactured and sold by Boston Scientific Corporation. Other woven medical devices are disclosed in U.S. patent application Ser. No. 09/496,243, filed Feb. 1, 2000 and entitled “Woven Intravascular Devices and Methods For Making the Same and Apparatus for Delivery of the Same” (hereinafter “first patent application”) and in U.S. patent application Ser. No. 09/495,984, filed Feb. 1, 2000 and entitled “Woven Bifurcated and Trifurcated Stents and Methods For Making the Same” (hereinafter “second patent application”), both of which are hereby expressly incorporated herein by reference. The ends of the strands of woven devices may be left free after the weaving process is complete. If delivered into an internal body structure, such as a blood vessel, in such a condition, the free strand ends may damage the internal body structure.
Different steps have been taken to secure the free strand ends of such woven devices. Some methods that have been used in this regard include securing free strand ends using laser welding, soldering, and brazing. These traditional methods may raise issues about material biocompatibility, and may cause problems such as loss of product structural integrity due to a change in material characteristics during the securing process, and the possible introduction of a foreign body into vessel should a piece of welding or soldering material break free. These problems are not intended to be exhaustive, but rather are among many that tend to impair the effectiveness of previously known methods of securing the free strand ends of certain woven medical devices. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that previous techniques of securing the free strand ends, also described herein as securing the intersection formed by two or more crossed strands, of certain medical devices have not been altogether satisfactory.